Cellulose ester product



Patented Mar. 15, 1938 UNITED STATES PATENT orrics CELLULOSE ESTER PRODUCT No Drawing. Application December 4, 1935, Serial No. 52,877

8 Claims.

This invention relates to colloidized products prepared from cellulose esters containing fatty acid groups of 3-4 carbon atoms which esters have a content of at least of propionyl and/or butyryl and which have been hydrolyzed to-an acyl content of 1% to 2 acyl groups for every Cc unit of cellulose. These products have been found to have excellent dyeing properties.

In the manufacture of yarn from cellulose acetate, it has been observed that the dyeing properties of the yarn improve with a decrease in the acetyl content of the acetate from which the yarn is made. However, with a decrease in the acetyl content of the cellulose acetate, the moisture absorption increases and the wet strength of the resulting yarn decreases, low moisture absorption and high wet strength being valuable characteristics of yarn; Also, with continued hydrolysis, the cellulose acetate ceases to be soluble in pure acetone, which is commonly employed as the spinning solvent. This increased susceptibility of cellulose acetate to the action of moisture is indicated by its increase in solubility in acetone containing a considerable percentage of water.

We have found that if cellulose esters having a content of at least 20% of acyl groups of 3-4 carbon atoms are hydrolyzed to a point where -dyes,'are still soluble in acetone and have a wet strength comparable to that of a good quality cellulose acetate yarn. These esters may be defined as those which have been hydrolyzed to an acyl content of 1% to 2% acyl groups for every C6 unit of cellulose.

By using these cellulose esters in the preparation of yarn, a product may be produced having the wet strength and resistance to moisture of an acetate yarn but which dyes better than any type of acetate yarn and even better than the yarn of an acetate which has been hydrolyzed beyond its acetone solubility range. These cellulose esters may also be employed for the preparation of a film base or a backing for a film base, which film base or backing is readily susceptible to the action of dyestuffs, and thus may be readily colored. The cellulose esters which may be employed for this purpose are cellulose propionate, cellulose butyrate, cellulose propionate-butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetatepropionate-butyrate prepared from, tri-esters having a content of at least 20% of acyl groups of 3-4 carbon atoms and which have been hydrolyzed to an acyl content of 1% to 2 acyl groups for every C6 unit of cellulose. The yarn from these esters can be spun from their solutions in acetone, acetone-water, acetone-alcohol, ethylene chloride-methyl alcohol, etc., preferably by evaporative spinning.

An example of a method by which yarn may be prepared from a solution of a cellulose ester in an organic solvent is described in Stone Patent No. 2,000,047, patented May '7, 1935.

As pointed out above, the products prepared from these esters have excellent dyeing properties. This is shown by the following data, in which a number of samples of various cellulose esters were spun into the form of yarn from their solution in acetone and were tested for affinity with dye.

Under Depth of color the samples are numbered in accordance with the order of their depth of color. There was a considerable difference in the depth of color between Sample C and Sample E, the latter being considerably lighter than the former.

As may be seen from the above table, the first four examples are of yarn from esters containing less than 2%, acyl groups for every Cc unit of cellulose, and the yarn prepared therefrom was readily susceptible to the dye. However, the fifth example is of yarn from an ester which has not been hydrolyzed enough and therefore contains a greater number of acyl groups than specified. It was found that this ester was not readily susceptible to the action of the dye. The next two examples were of yarn prepared from cellulose acetate. These samples dyed even lighter than the sample of acetate-propionate having more than 2% acyl groups for every Cs unit of cellulose.

The dyeing was carried out as follows, all of the samples having been put thru together:

The samples of yarn the weight of which totalled about 100 gms. were placed in a scouring bath consisting of 3 liters of water, 6 gms. of neutral soap and 3 gms. of aqueous ammonia (28% solution) which bath was maintained at 80-85 C. The yarn was gently agitated therein for 30 minutes. It was then removed from the scouring bath and rinsed free of soap.

The yarn was then placed in a dyeing bath, at room temperature, consisting of S. R. A. blue IV powder grams 0.5 Soda ash do .45 Turkey red oil c. c 6 Olive oil soap grams 2.25 Water liters 3 The whole was then heated so as to bring the temperature up to 80 C. in approximately 20 minutes. The temperature was held there for about minutes during which the bath was gently agitated. The yarn was then removed from the dye bath and washed With water to remove the dyeing liquid from the dyed yarn. Each sample of yarn was inspected for depth of coloring with the results tabulated above.

The dyeing of cellulose ester yarns is well known and any of the dyes which are employed for this purpose are suitable for use in dyeing the yarn or other products of the present invention. 7

In the coloring of a sheeting or photographic film base composed of cellulose acetate, diificulty is usually encountered. It has also been attempted to color cellulose acetate film base byv incorporating the dyestufi in the solution there of. However, this has also been found to present difiiculties in coloring. In order to eliminate these difficulties and still retain the low-inflammable characteristics of cellulose acetate film, a layer of cellulose acetate-propionate having 1% to 2 A; acyl groups per C6 unit of cellulose, the tri-ester of which has at least of acyl groups of 3-4 carbon atoms, may be applied to the cellulose acetate film and this coating may be readily dyed with spirit-soluble dyestufis to form a colored film base. If desired, instead of coating cellulose acetate film with a layer of the cellulose acetate propionate or the like, the latter ester may be employed to make the film base itself, and thus replace the cellulose acetate film. As pointed out before other cellulose esters having a suificient content of acyl groups of 3-4 carbon atoms and hydrolyzed sufficiently may be employed in this connection instead of cellulose acetate-propionate.

The solutions of these esters may also be employed in other connections, such as in the coating of fabrics, wood, or other objects, especially where an easily dyed coating or impregnated material is desired. These esters may also be incorporated with other cellulose esters, the dyeing properties of which are not as advantageous, in order to improve the susceptibility of the resulting product to the action of dye.

We claim as our invention:

1. A dye-susceptible colloidized cellulose ester product comprising an organic acid ester of cellulose prepared from a tri-ester having at least 20% of acyl groups of 3-4 carbon atoms, which ester has been hydrolyzed to an acyl content of 1% to 2 acyl groups for every Cs unit of cellulose.

2. A dye-susceptible yarn comprising filaments of an organic acid ester of cellulose prepared from a tri-ester having at least 20% of acyl groups of 3-4 carbon atoms, which ester has been hydrolyzed to an acyl content of 1% to 2 A acyl groups for every Cs unit of cellulose.

3. A dye-susceptible sheeting comprising an organic acid ester of cellulose prepared from a triester having at least 20% of acyl groups of 3-4 carbon atoms, which ester has been hydrolyzed to .an acyl content of 1% to 2 A; acyl groups for every C6 unit of cellulose.

4. A dye-susceptible photographic film base containing an organic acid ester of cellulose prepared from a tri-ester having at least 20% of acyl groups of 34 carbon atoms, which ester has been hydrolyzed to an acyl content of 1% to 2 acyl groups for every Cs unit of cellulose.

5. A dye-susceptible colloidized cellulose ester product comprising cellulose acetate-propionate prepared from a tri-ester having at least 20% propionyl content which has been hydrolyzed to an acyl content of 1% to 2 A; acyl groups for every Cs unit of cellulose.

6. A dye-susceptible yarn comprising filaments of a hydrolyzed organic acid ester of cellulose containing approximately 23-10% acetyl and 40% acyl groups of 3-4 carbon atoms, which ester contains 1% to 2 acyl groups for every Ce unit of cellulose.

7. A dye-susceptible yarn comprising filaments of hydrolyzed cellulose acetate-propionate-butyrate which has a content of 1% to 2 A acyl groups for every C6 unit of cellulose, the propionyl content being approximately one-tenth of the butyryl content.

8. A yarn comprising filaments of hydrolyzed cellulose acetate-propionate-butyrate containing approximately 7% acetyl, 3% propionyl and 30- butyryl.

CARL J. MALM. CHARLES R. FORDYCE. 

